Piston, particularly for internal combustion engines



1958 G. F.'W. LENGNICK ,86

PISTON, PARTICULARLY FOR INTERNAL COMBUSTION ENGINES Filed March 2, 1954 INVENTOR.

GEORGE EW.LENGNICK. BY fiwz/ MW ATTORNEYS PISTON, PARTICULARLY FOR INTERNAL COMBUSTION ENGINES George F. W. Lengnick, :Stuttgart, Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkhelm, Germany The invention deals with a piston, particularly for internal combustion engines, the skirt of which shows recesses on its opposite sides in the direction of the gudgeon pin axis. a r

An object of the present invention is to aim at an oil consumption and a wear in; connection with pistons of) 1internal combustion e gines which are as low as possr e.

Another object of the present invention is a piston having a high rigidity in spite of the arrangement of recesses in its skirt.

As it is well known in the art, pistons show a tendency of tilting in operation, thus causing a considerable wear with a recognizable reduction of the engine power; In order to avoid these disadvantages, slipper pistons have been suggested. 'I-hese pistons are provided with recesses or slots extending from the bottom edge of the piston about up to the gudgeon pin boss so as to leave only a narrow wedge-shaped portion of the piston skirt on the thrust bearing surface of the same, i. e., in the direction perpendicular to the gudgeon pin axis. Apart from the decrease of the rigidity ofthe piston, engines equipped with pistons hitherto suggested show a high oil consumption, because the lubricating oil arriving at the freely exposed surface of the cylinder bore within the range of the piston overcharges or overloads the oil control ring.

According to a feature of the present invention a continuous skirtis provided along the entire circumference of the piston, the bearing surface of the piston having recessed portions extending upwardly from the bottom edge of the piston. According to other features of the present invention the recessed portions takeup such a portion of the circumference of the piston that their width is larger, preferably many times larger than the diameter of the gudgeon pin bosses located on the same sides of the piston. On the other hand, the recessed portions terminate in front of the groove of the compression ring or oil-control ring, respectively, adjacent to said boss. In this way the cylinder bore is covered at least for a short stretch over the entire circumference of the piston skirt, and, accordingly, the oil consumption of the engines equipped with such pistons will remain moderate. Owing nited States Patent 9 an internal combustion engine in accordance with the present invention,

Fig. 2 is a cross-sectional view through the piston taken along the line IIII of Fig. 1,

Fig. 3' is a side view of another embodiment of a piston in accordance with the present invention, and

Fig. 4 is a cross-sectional view through the piston taken along the line IV-IV of Fig. 3.

The piston consists of the usual cylindri-c body lwith the gudgeon pin 2 put through transversely. In the crown 1a of this piston there are arranged some grooves 3 and a groove 4 for receiving usual compression rings and, a lower scraper ring, respectively. The groove 4 may com municate with the hollow interior of the piston 1 by way of transversal grooves 5. According to the invention the bearing surface of the piston shows recessed portions with none or substantially no openings in the piston skirt to the recesses no wear higher than that observed with Wall within the extent of the piston skirt 1b on the sides where the gudgeon pin'bosses are' located. The depth of the recessed portions 6 normally amounts to from approximately 0.008" up to 0.08" depending on the diameter of the piston and the wall thickness of the piston skirt, the lateral limit of the recessed-portion being defined by edges preferably running parallel to the gudgeon pin axis. The width of the recessed portion 6 amounts to at least as much as the diameter of the gudgeon pin boss, but preferably as much as a multiple of the diameter of the gudgeon pin boss 2a.

In the case of the embodiment accordingto Fig. 1 the recessed portion 6 is just so highthat its top contact edge, preferably running horizontally, just touches the gudgeon pin boss. Furthermore, the recessed'portion takes up an angle of (Fig. 2).

In the case of the embodiment according to Figs. 3 4 the recessed portions 6 pass by the gudgeon pin boss 2a so as to form'lateral pockets 60 which extend near the scraper ring groove, but terminate in front of it. In this way the lubrication of the gudgeonpin is similarly favored as with the prior art construction in which lubricating oil passages lead from the gudgeon pin boss to the bottom edge of the piston and communicate with the groove of the lower compression ring or of a scraper ring through inclined by-pass channels bypassing the gudgeon pin boss. Simultaneously, however, the wear will also be decreased and the'engine power increased.

In particular cases, by way of example, for long-stroke engines, the recessed portions-may be so wide that only a narrow strip 10 remains as bearing surface on the piston sides under higher pressure, i. e., perpendicular to the gudgeon axis. l t

The invention is not restricted to the illustrated embodiments. Thus, the single-features in Figs. 1 and 2 may, at will, be combined with the features of Figs. 3 and 4 by providing, for instance, a narrower and longer recessed portion or a wider and shorter recessed portion.

What I claim is: g

1. A slipper piston with' a piston crown, a continuous skirt extending over the whole circumference of the piston, a transverse hole for a gudgeon pin, arecessed wall portion of predetermined and uniform depth being provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite one another, each recessed wall portion extending from the bottom edge of thepiston and forming a portion of the circumference of the piston skirt on both sides of a plane passing through the axis of the gudgeon pin holein the direction of'the piston axis, said piston skirt l atented Dec. 9, 1958 with said recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt.

2. A slipper piston with a piston crown, a continuous skirt extending over the entire circumference of the piston, a transverse hole for a gudgeon pin, a recessed wall portion of predetermined and uniform depth being, provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite one another, each recessed wall' portion extending from the bottom edge of the piston and forming a portion of the circumference of the piston skirt on both sides of a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, each recessed wall portion having a width larger than the diameter of the gudgeon pin boss, said piston skirt with said recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt.

3. A slipper piston with a piston crown, a continuous skirt extending over the entire circumference of the piston, a transverse hole for a gudgeon pin, a recessed wall portion of predetermined and uniform depth being provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite one another, each recessed wall portion extending from the bottom edge of the piston and forming a portion of the circumference of the piston skirt on both sides of a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, the recessed wall portions extending over a greater are of the piston circumference than the unrecessed portions thereof remaining between the recessed portions, said piston skirt with said recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt.

4. A slipper piston with a piston crown, a continuous skirt extending over the entire circumference of the piston, a transverse hole for a gudgeon pin, a recessed wall portion of predetermined and uniform depth being provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite one another, each recessed wall portion extending from the bottom edge of the piston and forming a portion of the circumference of the piston skirt on either side of a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, the recessed portion extending over an angle of at least 90, said piston skirt with said recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt.

5; A slipper piston with a piston crown, a continuous skirt extending over the entire circumference of the piston, a transverse hole for a gudgeon pin, ,a recessed wall portion of. predetermined and uniform depth being provided only in the bearingrsurface of the skirt of the piston each on sides of the piston opposite another, each recessed wallportion extending from the. bottom edge of the piston and forming a portion of the circumference of the piston skirt on either side of a plane passing through the axis of thegudgeon pin hole in the direction of the piston axis, the recessed portions being delimited outwardly by edges running parallel tov the piston axis, said piston skirt with said recessed wall portions shielding the interior of said piston substantally over the entire length of said skirt.

6. A slipperpiston with a piston crown, a continuous skirt extending over the entire circumference of the piston, a transverse hole for a gudgeon pin, a recessed wall portion of predetermined and uniform depth beingprovided only in the bearing surface of the skirt-wall of the piston each on sides of the piston opposite another, each recessed wall portion extending from the bottom edge of the piston and forming a portion of the circumference of the'piston skirt on either side-of a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, the recessed wall portions extending nearly. up to the gudgeon pin bosses, said piston skirt with said recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt.

7. A slipper piston with a piston crown, a contmuous skirt extending over the entire circumference of the piston, a groove for an oil scraper ring between said crown and said skirt, a transverse hole for a gudgeon pin, a recessed wall portion of predetermined and uniform depth being provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite another, each recessed wall portion extending from the bottom edge of the piston and forming a portion of the outer circumference of the piston skirt on either side of a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, said piston skirt with said recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt.

8. A slipper piston with a piston crown, a continuous skirt extending over the entire circumference of the p1ston, a groove for an: oil scraper ring between said crown and said skirt, a transverse hole for a gudgeon pin, a recessed wall portion of predetermined and uniform depth being provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite another, each recessed wall portion extending from the bottom edge of the piston and forming a portion of the outer circumference of the piston on either side of a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, the recessed wall portions having a width larger than the diameter of the gudgeon pin bosses, said piston skirt with said recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt.

9. A slipper piston with a crown, a continuous skirt extending over the entire circumference of the piston, a groove for an oil scraper ring between sa1d crown and said skirt, a transverse hole for a gudgeon pin a recessed wall portion of predetermined and uniform depth being provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite one another, each recessed wall portion extending from the bottom edge of the piston and forming a portion of the outer circumference of the piston over at least an angle of 45 on either side of a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, said recessed wall portions being further delimited on the outside thereof by edges running parallel to the piston axis and extending nearly up to the gudgeon pin bosses, said piston skirt with sa1d recessed wall portions shielding the interior of said piston substantially over the entire length of said skirt. I

10. A slipper piston with a crown, a continuous skirt extending over the entire circumference of the piston, a groove for an oil scraper ring between said crown and said skirt, a transverse hole for a gudgeon pin, a recessed wall portion of predetermined and uniform depth being provided only in the bearing surface of the skirt of the piston each on sides of the piston opposite one another, each recessed wall portion extending from the bottom edge of the piston and forming a portion of the circumference of the piston over an angle of at least 45 on either side of. a plane passing through the axis of the gudgeon pin hole in the direction of the piston axis, said recessed portions being further limited on the outside thereof by edges running parallel to the piston axis and terminating in front of said ring, groove, said piston skirt with said recessed wall portions shielding the interior of said piston substantially ovr the entire length of said skirt. I

11. A slipper piston with a piston crown according to claim 1, further comprising a groove for an oil scraper ring between said crown and said skirt, sa1d References Cited in the file of this patent UNITED STATES PATENTS OReilly Aug. 3, 1926 Day May 22, 1928 Covert Aug. 11, 1931 Malina Oct. 24, 1939 Venner et a1. Feb. 14, 1950 Moore July 4, 1950 

